[Feature Request] - Add model for setup-python GitHub Action

Description

Macaron currently does not have models for the setup-python GitHub Action, which is commonly used in CI workflows to specify the Python version. Adding support for this action would allow Macaron to more accurately analyze and reproduce Python-based projects that use GitHub Actions for builds and tests.

Proposed Feature

Create a model in Macaron for the setup-python GitHub Action that can:

Detect the specified Python version(s) in the workflow.
This model should align with how other GitHub Actions (e.g., setup-java) are handled within Macaron.

Use Case

Many open-source Python projects use setup-python in their GitHub workflows. Without modeling this action, Macaron may miss critical environment setup information, leading to inaccurate or failed reproduction attempts. Supporting this action will enhance Macaron's ability to analyze Python projects and generate correct build specifications.

Start in src/macaron/slsa_analyzer/ci_service/github_actions/analyzer.py, using the setup-java handling linked in the issue as the reference point. Add setup-python support that detects specified Python versions in workflows, then verify that Macaron captures this information for Python project reproduction.